The Talitroidean Amphipod Family Hyalidae Revisited, With Emphasis on the North Pacific Fauna: Systematics and Distributional Ecology

118 Pages·2002·96.7 MB·

by  E L Bousfield

AMPHIPACIFICA VOL. 3 NOJ Nov. 15, 2002, 17
THE TALITROIDEAN AMPHIPOD FAMILY HYALIDAE RE\TSED, WITH EMPHASIS
ON THE NORTH PACIFIC FAUNA: SYSTEMATICS AND DISTRIBUTIONAL ECOLOGY.
E. L. fiousfieJd^ and E. A. Hendrycks^
ABSTRACT
Analysisill hyalidspeciesofcmsiaJ watersofihe NorthFiieincBasin ha^don newly recognizedcharecier^
(e i.,hydrcxlynanniicIttbesof gnathopexts,surgesetaandnotchofiheposteriormarginofthebasesofpemeopods
5-7),andlhi>serecently utilizedelsewhere(e.g.,prc-annple\jn.gnotchofperaeon2female,posteriormarginalcusps
ofcoxae I-4,andformofbrcsxl lamellaeandmarginal selae), necessitaiedesiablishmcnlofnew-genericconcepts
andfamily reconsiitutionona world wide basis. Hyalidae hereencompasses subfamilies Hyallnae Raihke(new
status)basedon Hyaie Rathkesens, str.: KurilnaeJ, L. Barnard (newstatus),basedonKuriatongimana Scott^
Walkerand Micropyihici Krapp-SehitkeH;andllyaebeliinae new subfamily, ba.scd on HyacheHa torlugaeJ. L.
Barnard. Subfamily Hyalinaeencompasses two morphological-beliaviouraJ groupsofgenera: (1) a reigiively
primitivenaiatorgroup,hydrodynamically specializedforswimming,that includes Paraliorckeit&sShoemaker,
Pt&t&hyale n, g., Leiehutt J. L. Barnard, Hvaie Rathke sens, sir., and the enigmatic genus Neobuk Hsiswe]]
{Frotohyateencompasses n,subg.,Diptohyalen,subg,.Leptohyalen.subg.,andPromhyaie^nominate
subgenns:and(2)arelativelyadvancedmaLnlyintertidalsaltaiorgmup(speciali/cdforjurripingorspringingin air)
thatencompass^ Farhyate Stebbing, Ptiiohyale n. g,,Apohyak n. g., Rujfohytdt n. g., and H^rejuhyak n. g.
Newly described fromthe PacificcoastofNorthAmericaare: Parailorchestesalmkemis n.sp.. F.asritmta n
sp.,P. n.sp.,F.kahstai n.sp..,F.kbiondi n..sp.,P.miniman..sp.,P.nudan.sp.,/*.subcaiinam n, sp.,
and F*irhpinosa n, sp. Also redescribed arc P,(nmriema Bousfield. andthreewesiem N. PaciRc species: P.
asiaiicaTzvetkova.P.ochoiensis(BrEmdt)andP.zitdUna{Derzha-iin). Protohyakencinnpasseswithinsubgcnus
Boreohyak the fejllowing N. American Pacific species; F. fB.) kiwaturiin. sp.,F. (B.Jijarrettae n. sp.,/*. (if.)
iamh^rtin. sp-i P^ (BdnMonon^misn.sp., P.fB.)oclaihn, sp.,P. fB.)ocakt/a u, sp.,jP.(B,Ji s^ticon\is n.sp.,
and within themonoiypicsubgenusLept&hyak^F.{L>iongipaipa, n. sp. SpecieswithinsubgenusProtohyuk
tHJCurin soulhcm(.'alifomiaand BajaCaliforTiia(Mexieo),includingF.(P.Jcamika(Barnard),P. iP.frequens
R
(Stout), fP. ) ffiofin n. sp,,and P. iP.)yaqui (Barnard). North .American Pacific saltaling hvalids include
Apohyol^Qficeps(Barnard),A.caUfomkafBarnard),A. (f)ana)andPtilohyakpiumuiosa(Stimpson).
Keys, jlliLsirations,andnumericaltaxonumical anddistributionalanalyse.-iarealstrpro\ided, I'hecold-tempcmU;
hyalidsofeasternandwestern Nonh PacifichyaJidsarenotclosely related,andthewarm-temperatehyalidsofthe
western Pacifichavecloseraffinitieswith ihiiseofthecentral Pacific(Hawaiian)archipelago.
INTRODliCnON izedcompendiaincluding tlioseofHickettsandCalvin
SpeciesofHyalidaeoccurmainly intertidaJlyandin (1948), Smith 8c Carlton (1975), Austin. (1985) and
shallow lIttoraJ marine waters. Although not usually Staude(]987)provideregional listsand keystospecies
conspicuous becauseoftheirrelatively small sizeand ofthe northwestern Pacificcoast.
somewhat concealed life style, these aquatic Essential elementsofthepresentstudyofthe North
talitroideans were nonetheless among the earliest Pacific hyalids were first summarized by Bousfield
amphipod species recorded and described from the (1981). As this summary was to beaccompanied by
coastsofEurasia{e,g.,Rathke 1R37;Kroyer 1845:Bate full taxonomic treatment of neiv taxa elsewhere* the
856) and newly colonized Pacific continental coasts Ulustrations were small, unaccompanied by formal
1
during the i9th century (e,g-, Dana 1853: Stimpson diagnoses*oridentificationoftypespecimensandtype
IS57). Nineteenthcentury recordsweresummarized locaJiries. Regrettably,theintendedpubticarionseries
by Stebbing(19i}6) and early 20th century records by IBulletinoftheNationalMuseumofNatural Sciences*
Holmes(I Stout(1913),andThorsieinsoti(1^1), Canada) wasdiscontinued shortly thereafter. The in-
Theauthorsareenonnously indebtedtothelate J.L. tendedtreatise(Bousfield MS)*bearingessentiallythe
(Jerry) Barnard whose publicationson the littoral ma- sametideasthe present,did notappear,thusrendering
rineamphipodsofCalifornia.Baja.Hawaii,andGalap- die presentpaperineffectan ’'interruptedpublication"
agos regions (1970, 1974,1979), and earlier studies (ICZN 1985,article 23). Consequently, the names
(1952, 1954, 1955, 1962, 1965, 1969b, 1975) liiid a (1981 ) that were apparently considered unavailable
solidfoundadonforthepresentInvestigaihon. Popular- (nominanudafby mostsubsequentauthors, including
' Research Associate, RoyalOntarioMuseum,Toronto,ON, CAN MSS 2C6;
-Research Division,Canadian MuseumofNature,Oltawa,ON,CAN K F6P4
I
2 7
AMPHIPACIFICA VOL. 3 N0.3 Nov. 15, 2001 18
definitive gammaridean amph(|X)d treatments (e.g*, Taxonomic work on CMN amphipod collections
Barnard & Karaman 1991; jshimarxi 1994) are herein wasperformedinitiallyby BLBasastaffmemberofthe
validated bj' tbrmaJ description(iCZN). Thepi^scnt National Museum of Natural Sciences at the Holly
study is intended, therefore, to complete formal de- Lane Laboratory Ottawa, during the period 1979-
,
scription of these new taxa under new names, and ]985,andmorerecentlyasavisiLingscientist. OriginaJ
expanddieworkintoa preliminaryworld-widereview lineillustrationswerepreparedwiththecapableassist-
ofthe entirefamily Hyalidae. anceofartistRoy E.Zfttin,Capeitlno,California- The
Taxonomic knowledgeofthefamily has increased authorsare indebtedto MarjorieBousfieldfortransla-
rapidly elsewhere. Thtts,during the past 35 years the tionsofthe Russian literature.
familyhasincreasedfrom60describedspecies(Barnard The work wascarriedoutmainlyinresearchlabora-
1969a) to the present -110 species in 12 genera and toriesoftheCanadianMuseumofNature,Ottawa. The
three subfamilies. authorsare especially grateful toassistantcollections
C
managerJudith Price inretrieving,cataloguing,and
ACKNOWLEDGMENTS labelingof CMN amphipod material and toMr. Noel
,
Forassistancewithfieldworktheauthorsaregreatly AlfonsOt CMN, forassistance in computerized map
indebted to regional marine laboratories, nouibJy the preparation. Mr. Pierre Marcoux provided most valu-
Pacific Biological Statiom Nanaimo, B.C., the PaciHc able curatorial, research, and artistic assistance that
Environmental hmitute. West Vancouver, B. C the measureably improved thescope ofthe study.
Bamfteld MarineStation, B.C..and theFriday Harbor Table1.Abbreviationsusedin figuresand tables:
Laboratories, WA. Much of the detail has been ac- A1-2 - antenna L 2
knowledged in previous station lists (below). Drs. BAS - basis
Craig P. StaudeandColinB. Levings,andthelate Dra. BRSET hroexisetale)
CARP carpus
Josephine F. L, Hart, and Daniel B. Quayle were
CLSP ololhes-pinspine
especially helpful with the field work. CX coxal plate
Theauthors are grateful to Drs. PeterSlattery and ixm.
dactyl
Charles E. O'Clairforproviding valuable study mate- EPI-3 abdonvln. side plates ],.2.3
rial from the BeringSeaand Aleutian Islands regions. GN 1-2 gnalhop(,)ds 2
IT
Dr, Nina Tzvetkova, Zoological Museum, St Peters- HD head
burg, provided helpful commentary and Joan of valu- rSCH ischium
ablewestern North Pticific material. We much value LFT left
thecareful researchassistancetindcommentaryofDrs. LI. lowerlip(labium)
MD
Shin-ishi Ishimaru,A. Hirayama,andTakehitoHiwatari mandible
MER merus
iwnhgoskenopwublleidcgaetioofnswheastveerbneePnaciinfsitcrruemgeinotnaallianmdpehvletlxo>pd- MMXXPLD2 maxilla 1.
maxilliped
faunas. Dr, TraudI Krapp-Schickel has helped espe-
P3-7 peraeopods3,4, 6.
daliyinclariTyingtheTaxonomicstatusofgenusHyaie. P-AMPhfTCH preamplexing notch
Drs. Cristiana Serejoand Yoko Wakabara have pro- Pt^PD picopod
vided mosthelpful material,commentaiy,andusageof PLP palp
theirpublicationsinclarifyingtaxonomicandmorpho- PRPD propod
logical aspects of tropical .Atlantic genera. We are RET retinacula
especiallygratefultoDr. DaleR.Calder,RoyalOntario R1 right
Museum,Toronto,forhisadviceonimplementationof SGSET surge seta
ICZN rulesvis-a-vispreviouslyunavailabletaxonomic SP spine
T
iclson
names. Mr.Thurlow ArbuckJe, Ottawa, directed the
senior author to sources of information on hydrody- UE-.1 uropod 1, 2, 3
lit. upperliptlahrum)
namicfeaturesofhulldesignin poweredoceanvessels, t.lROS urosome
and thelfprobableapplicability totheoverall stream- X enlarged
lined form of coxal and basal plates and anierodistal em immature
lobesof basal and ischial segmentsofthe gnathopods jiiv - juvenile
oftheamphipod crustacean. - subadulL
AMPHlPACinCA VOL. 3 N0.3 Nov. 15. 20&2, 19
MATERIALS AND METHODS. Gnathopod small, regularly subchelate, propod
1
Stationlists pertinenttofield mLiterial utilized inthis and/ordactyl variouslysexuallydimorphic;basisoften
study are provided in Boysfidd (1958, 1963, 1968); with anterodistal hydrodynamic lobe; dactyl simple,
Bousfceldi& McAllister(1962);andBousfield&Jameil occasionally bidentateorbifid (male). Gnathopod 2
&
(198!). Numbers ofspetirraens colkcied at each sta- usually strongly sexually dimorphic; basis ischium
tion are given in parentlieses. oftenwithhydrodynamiclobes;carpal lobedeveloped
Analysesofpossiblephyletjcrelationshipsof hyalid (female)ormostly lacking(male); propod and dactyl
generaandspeciesutilizea semi-phyleticmodification stronglydeveloped (male).
ofthe UPGMA system of Sneath and Sokal (1973). Peraeopods 3-7 regularly ambulator)7'perching" or
Charactersandcharacterstatesareillustrated mainlyin prehensile(Hyacheliinae). Peraeopesds5-7essentially
Figures 1-4. Theseareordered phyleiicallyby values homopodous; bases broad, hind margin variously
of0, and2forplesiomorphic,intermediate,andapo- crenulated, usually with submedian notch and ‘^surge
1,
morphic states, respectively. The phyletic placement seta”; proptxt often with anterior marginal clasping
ofa given taxon is represented bya numerical sumof spinc(s); dactyl strongandsimple,orrelatively short,
character state values temred the Plesio-Apomorphic with strong innermarginal seta.
(P.-A.)Index of^'hichthemaximum valueistwicethe Hpimeral plates regular, w'eakly armed. Pleopod
numberofcharacters utilized. rami normally developed,natatory. Uropod I, pedun-
cle and rami subequat in length; peduncle often with
SYSTEMATICS
strongdistal spine{s): rami linear, marginally spinose.
Uropod 2 similar, smaller, outerramusoften shorter.
HYALIDAE Bulycheva Uropod3short,spino.se,essentially uniramous,orwith
inner ramus reduced toasmall lobe.
Hyalidae Bulycheva, 1957: 76;—BousBeld 1982; 269; Telson short,fully bilobate,lobessubtriangular.
-Bousfieid2001a: 104;-Serejo 2001; 480, Mature Female: Gnathopods regularly subchelate,
Hyalidae (part): Barnard Jk Karaman 1991: 366;— subsimilar. Brood lamellae variously subovate,
Bousfieid Sl Shih 1994: 129;-I.shimam 1994: 67;- sublunate,orsubrhomboidal inoutline, maigins lined
Lowry & Springthorpe 2002. with numeorus hook-tipped setae. Peraeon segment2
Hyalinae(Tatitridae)(part) Barnard 1972:167;—Grif- anterO'distal margin usuallywith pre-amplexlngnotch.
fiths 1976: 76,
Talitridae(|.>art)Stebhing 1906:523;—Gurjanova 1951; Habitatr Marinc Iiitoral,frce swimmingorintenidal
813. and saltatory,often associated with algae and marine
Talitroidea (part) Barnard 1969a: 463;—Barnard & grasses: nearly cosmopolitan (except polar region.^),
Barnard 1983: 16L along temperate to tropicaf mainly rocky, surf-ex-
|X>sed,hjgh"Salinityshores;afewspeciesareestuarine
Subfamilies: Hyalinae RathkeT837, restrictedstatus; and brackish-water, and members of one genus are
Hyachelnnae n. subfam.; Kuriinae Barnard, 1964, hypogean incoastal freshwaters.
new status.
Remarks: Implementation of names of taxa, newly
Diagnosis; Body smooth or posteriorly middorsally utilized In previous publications but taxonomically
toothed. Antennaewell developed;Antenna I longer unavailable, hereconform with rulingssetforth inthe
than peduncleofantenna2; gland cone small. 1CZN Code(1985and 1999),Sect. 18,Art.23, .Ap|>ar-
Mandible, left lacinia 5-S dentate. Maxilla I, palp entlyforthereasonoftaxonomicunavaiIabi1ity,Bamaixl
slender,!-2 segmented, Maxilla2, inner plate with I & Karaman(1991)andIshimaru(1994)didnotoraclude
(2) piumoseinnermarginal seta(e). MaxilJiped,plates i^ew species names proposed by Bousfieid (1981) for
well developed, palp large, occasionally sexually di- North American Pacific speciesofHyaie Rathkesens,
morphic (dactyl often with apical whip flagellum in lat.andPamUorchestesShoemaker. AIthoughmostof
male). these species were again listed, and four new generic
Coxal plates 1^ normal, medium deep: posterior names added by Bousfieid (2(X)la), all but one name
marginal shelfandcuspvariouslydeveloped,reduced, remalnedtechnlcalIy as tuymhta nada. Theexcept!on
orlacking.Coxae5 slightly anterolobate. Coxal gills was Paraihrehest^i afmricana Bousfieid, 19RL re-
mediumtolarge, platedikeorsac-like. wgnizedandvalidated throughdetailedcomparisonof
. ,
AMPHIPACJFICA VOU 3 N0.3 Nov, 15. 2002. 20
its character states with those of the western Pacific ter states then considered significant. More recenliy,
Species, P.miatlmJzvcXkovA. 1990. [n foOowingthe alphabetcaJ compendiahaveincreasingly been super-
provisions of ICZN ruhngs (aboveJ, theauthors have seded by phyletically oriented generic- and famiJy-
herefuJtydescribed andfigured, and hence taxonom- Eeve! revisions in which new and important character
ieally validated, many ofthe original names; in some smtes have been recognized and the results supported
instances, however, alternate new names have been by numerical analysis. Since 1986. these studies,
proposed, as detailed in the following descriptiveac- includingthepresent,have increasedtheworld total by
countsofhyaJid subfamilie.s, generaand species. -20% more speciesand -30% moregenera. We hope
Almostuniquelyamong malacostraeancrustaceans, therefore, that the present comprehensiveanalysis of
thebasicamphipodbodyformisdesignedforsustained familyHyaiidaewill moreconciselydefineitsdiagnos-
rapidforwardswfrnmingfBoudnas 1991). Mysidaceans ticcharacter states and generic inclusions, and under-
alsopropel themselvesforward,butsincethebodyand line its morphological. distributional-ecoiogicaJ, and
appendages are streamlined, the forward motion is behaviour^iJ differences from other families within
short,jerky,and unsustained(personalobservationson supertamilyTalitroidea.
spccimensofPmmusflexuostiiinacfnaria), AIthough
synchroflELsh, cinephoiographic evidence is not yet
available, a primary functionofthe subsimilar, large- Subfamily Hyalinae restrictedjjtatus
plated peraeopods, overlapping forwards and back-
wardsfromthe"shoulder"or”beam''segment(peracon Hyalinae (part) Barnard 1972:167;-Griffiths 1976;
5).would appeartobestreamliningofthelateral body 76.
surfaces during swimming. The large a^unded basal
platesofperaeopods5-7 mayalsoservein rudder-]ike Typegenus: Hyaic Rathke, 837.
1
steeringand/or "braking" action by meansofanalters
nate,orsimultaneous,conlmlledoutwarde.xtensionof Genera: Apohyalen.g. (p, 104); Hyak Rathke. 1837
their trailing edges. The lobes ofthe bilobate telson (p.9);LeiehnaBarnard, 1970(p,92);NeobiileHasvvell
may also serve in steering and/or elevation during 1880(not treated); Paralhrchestes Shoemaker, 1941
swimming. Such presumably adaptsmembersoffam- (p.36);FarhyakStebbing 1899fp 96);Frot&hyaie n.
ily Hyabdaefor swimmingandbenthic "perching’' (of g. Cp. 62) \B&teohyale n. subg.; Diplohyate n, subg,.
Steele 1988) in the strongly lotic conditions of surf- l.epmmhyaien. subg.; Protohyak nom. subg.|; Pn'to-
exposedcoastal marinelittoralandsublitloraf habitats. ftyak rt. g. (p. 98); Ru/f^hytik n. g. (p. 1 16);Serejo-
By contrast- described members ofclosely related Ijyak n. g. (p, 114),
family Hyalellidac Bulycheva (see Hendrycks
Bousfceld 2001) are ambulatory, algal-dwelling, and Diagnosis: Small to medium large, free-living, mor-
semi-fossorlal, mainly in temperate and tropical ma- phologically and bchaviourally basic members ofthe
rtneandfreshwatcrsedimentarv'bottoms. InalIhyale!Iid Talitroidean Reptantia. Combinational diagnostic
species, the basal and ischial segmentsofgnathopnds characterstates include: Antenna 2 medium toelon-
&
I 2 (both sexes) totally lack anterodi.stal hydrody- gate.
namiclobes:thebasal segmentsofperaeojxxls5*7lack Coxal plates 1-4. posterior marginal "shelf and/or
po.sterior jnarginal notch and "surge seta"; the disto- cuspoften stronglydeveloped. Coxal gills large,plate-
laterat and disiomedial peduncularspinesofuropod ! like orsac-1ike, Sternal gi]1s Jacking
are not enlarged; and the telson lobes have become Gnathopods I & 2subchelate, strongly differing in
basally fused fe.g,, in Ailorchejites)ortotally fusedas fonn and size (male), subsimilarffemale): gnathopod
a solid plate (e.g., in Hyaieiia, P/4rhyaieIki), and of 1 weakJy.and gnathopod 2 usually strongly sexually
possiblydifferent primaryfunction. Freshwatermem- dimorphic. Hydrodynamic lobes ofbasisand ischium
bers of family Hyalellidae possess stemaJ gills, and of gnathopods variously developed (both sexes)
often processjferous body segments, but less robust Peraeopods 5-7; basis broad, hind margin often
peraeopodsand urop<xls. crenulated, with single notch and "surge seta",
The website versionof Hyaiidae by Lo^vry (1999), Pleopodssleiider, with reduced retinacula, butfully
apnodseld-boywrByarannadrdSp&rmKgatrhaomrapne((12909011).) fTohlleovwesrsthiaotnpwraos- dsteovuet,lompaerdgipnlaulmlyosierr-esgeutloasrelyrasmpii.noUsreop(noodtsslIe&nde2r,,rsearmii-
apparently notsubjecttonumerical analysisofcharac- ally spinoseand natatory). Uropod 3 uniramous or
AMPHIPACIFICA VOL. 3 NO,3 Nov, 15. 2002, 21
weakly biramotis, Telson short, fully bilobate. Brood swimming decapods are located mainly on the
lamellae large, broad,variously subovate to cephalothorax and pointanteriorly.
subrhomboidal, Preainpleining notch present. Areviewoflimitedinformationandtheoreticalcon-
siderations concerning the hydrodynamics of garti-
Remarks: Subfamily HyaJinae encompasses al] but maridean amphipods* especially of members of
threedescribedspeciesoffamilyHyalidae,assigned to superfamily Lysianassoidea, is provided by Boudrias
subfamiJies Kuiiinae and the Hyacheliinac, Within (1991). Supplemental nformationon stream]ining of
i
Hyalinae,thestoutstrongly spinosedistal segmentsof body and appendages in hyperiid amphipods (e,g„
the |>eraeopods would appear specially adapted to withinsuperfamilyPlatysceloidea)isprovidedbyBow-
grasping or perching upon algae and other bottom man and Gruner (1973), and on swimming speeds by
substrata located in strongly lode waters such as the Takeuchi & Wamnabe (1998), Sainte-Marie (1986),
surf 7om ofrocky beaches oftropical and temperate andtheoretical consideration herein.
marine regions. Broadly across generaof subfamily Hyalinae, the
Barnard(1972)andGriffiths(1974, 1976)departed basis and ischium ofgnathopods I ^ 2 are variously
fromtheoriginal falitroldeantlassificaloryconceptsof mtidified into large rounded lobes on the anterodistal
Bulycheva (1957) in relegating members offamilies segmental margins (nasiform lobe of Barnard 1979),
Hyalidae and HyalelSidae to subfamily status (as Theseoverlapontheadjacentsegments hydrodynam-
Hyalinae) within family Talitridae, However, evi- icaJIy forwaids{Fig. 4). Their marginsare rounded,
dence revealed by the present study provides greater presumably to facilitate flexing of the segments and
support forcontinued recognition of the orginal con- maintainstreamlinedformatnorma! anglesofflexure.
cepts of Bulycheva (loc. cit ). The lobeofthe basis is positionally anterodistolateral
whereasthe lobeoftheischium ismainlyanterolateral.
Charactersand Characterstates The purpose of the lobe has not yet been tested
The maincharactersand theirpossible stateswithin eXperimentaI[y, However, rnorphological and behav-
the Hyalinae(Figs, I-3)inquirelittleclarificationhere, ioural evidence indicates to us that iLs princi|>al func-
unlikethe fivecharacters discussed below. tion is to streamline margins ofappendages thatare
folded during swimming (see also Rgs. 5-7). The
L Hydrodynamic (h.-d.) lobesofthegrtathopuds. appellation "hydrodynamic" or "h.-d.^lobe is used
Thedesignofthe bodyandappendagesofamphipod henceforth in thisstudy.
crustaceans is imique within malacostracan crusta- Thedistribution and strength ofdevelopmentofthe
ceans in maximizing sustained forward swimming hydrodynamic lobeon the basal and ischial segments
speed. Hydrodynamicefficiency isfaciIitatedthrough of gnathopodis I & 2 is outlined graphically in fag. 4,
aforward-thrustingabdominal propulsionunit(3 pains Lobes are moststronglydevelopedw-ithinthenatatory
of picopods and tail-fan of 3 pairs of uropods and genus Profohyaie, and intermediate or least strong in
telson),and the stream!inedformandpositionofbody members ofsaltatory generasuch as Piihhyale. Apo-
platesandapfjendages. Suchincludes,inallamphipod hyaie and Parhyaie. Lobes are generally less w^ell
custaceans.theforward-overiappingofcoxal plates I- developedinthesmallergnathopodsoffemalesthanin
4,forward of''beam"' peraeon segment5 (widest body the larger gnathopods of males. Thus, even within
segment), and the backwards overlapping of basal, Proiohyale, the Ischial lobe is not w^ell developed in
coxal, and epimertd plates posteriorly from that seg- gnathopod 2 ofthe female, ischial lobes are weakly
ment. Coxa 5 (at the "beam"),universally within the developed In males of Parhyale and PfHohyaie, and
Amphipoda, overlaps neighbouring plates both for- apparently lacking In femalesofl^iehua and Hyale.
wards and backwards. In addition, body spines and Leiteand Wakabara (1989)studied devcIopmeniaJ
carinationsofswimmingamphipodsarelocatedmainly changes in the form and armatureofgnathopod 2 of
behind pemeon segment5 and point posteriorly. males and females of Protohyaie (P.} media (Dana).
By contrast, within caridean and most decapod Although theseauthors beautifully illustrated carpus,
shrimps (e.g., HofTuinisamerfcamts),the ’'beam" isat propodanddactyl,theydidnottreat thesignificanceof
abdominal segment 2. The epimeral plate of that corresponding changes in the anterodistal (hydrody-
segmentoverlapsadjacentplatesforwardand backards namic)lobesofthebasisandischium. Forthispurpose^
and facilitates rapid backwards propulsion ("escape pertinent parts of their figures are reproduced here
reaction") by the tail fan, Body and rostral spines of (Figs, 5 & 6), In the male(Ftg, 5),the h.-d lobeof
AMPHIPACIFICA VOL. 3 NO,3 Nov. 15, 2002, 22
Pleslomorphic Intermedkate Apomorphic
Rg, I. Characters and Character States of Hyalmae. A. Eye shape and antenna 2: semion;
B, Mandibular left lacinia: dentation C. Maxilla I: segmentation of palp;
&
D. Maxilliped palp: form ofdactyl (<S ). E> Coxa I. posterior marginal shelf cusp.
basis and ischium are in early development stages suggest that presenceOflarge hydrodynamic lobesof
duringthe6Lhto4thIastinstars.Theyattainful!y1obale thegnathopods isanadvancedcharacterstateinhyalid
and overlappingform in ihcfinal three instars, coinci- amphipods. .AstheirdevelopmenttosmalI sizeonly in
dentwithcompletefusion ofthe unguistothe bodyof intertidal saitaring species might result fromneotenic
thedactyi,and presumablyfull sexual maturity. In the loss, the phyletic significance oftliis character state
female (fig. 6), the h.-d. lobe of the basis follows a remainsmoot. Correspondingstudiesondevelopmen-
similar progression,and atiains fully lol>eate conditon tal stagesofgnathoptxj 1 (male),andthepreamplexing
1nthefinaltwoinsiars, Tiiatof the ischiumattainsonly notch of peraeon 2 (female) may prove instructive in
very small sizebythefinal instar. Suchevidencemight clarifyingthis point.
AMPHIPACIFICA VOL, 3 NO,3 Nov. \5 2002. 23
,
PlesiomorDhic Intermediate Apomorphic
4
.
R
Fig. 2. CKaracters and Character Stares ofHyaiinae. A. Coxa4: pusteror marginal cusp;
B. Gnathopod 1 (c?); preampiexmg spines ofpropod; C. Gnathopod 2 (eT): size ofcarpal lobe;
D. Peraeopods 5-6: size ofclasping spine; E. Dactyl of peraeopods 5-7: size of inner marginal seta;
F
Peraeopods 5-7: degree of broadening of segment4 (Literature sources).
ThepresenceofhydrodyitamiclobesintheHyalinae watersortidalcnirentsintosuitable benthic nichesfor
(and Hyacheiinae) is here considereda secondaiy hut food and shelter.
plesiomorphiccharacterstate. Its stronge-xpression in ElsewherewithintheTalitroidea,well-developedhy-
mainly free-swimming genera of Hyalinae (Fig. 4) drodynamic lobes have been detectedon diebasal and
especiallyin warm-temperateand tropical groupssuch ischial segments of gnathopod 2 of mature males of
as Protohyafe,tendstosupportthe presentconceptof most palustral generaoffamil> Talitridae |see fig,7 ,
hydrodynamic functionality. Thus, streamlining of and Bousfidd 1973, I984|, In these species that are
gnathopods in the swimming or "tuck" position pre- submerged for part or most of a tidal cycle (e.g.. in
sumably facilitatesa rapid escape reaction from fast- Porchestia, Proiorchesda, Uhlorhejsria) orthatoccur
swimminapredatorsorquickmovementfromioticsurf infreshwater(e.g., ChHtonorchestiaP the lobesoccur
AMPHrPACinCA VOL. 3 NO,3 Nov. !5, 2002. 24
PJ(^siomorphic Intermediate Apdmofplric
Rg. 3, Charactersand characterstates of Hyalinae,
A, Uropod K pedunculardistal spine(s); B. Uropod 3, numberoframi;
C, Telson, form and armatare; D, Brood plate (peraeopod 2, 9),formand margiua] setation.
anterodlstolateraOyonthebasis,andbothantem-later- pod I of family Aoridae (e.g., Aarordes) but not in
altyandanteromedialJyontheischialsegment(fig. 7). familyDulichiidaelsecBousfield, 1973;Barnard 5970a:
The lobes are generally less strongly developed in Barnard & Karaman, 1991 1. Within more primitive
bcachfiea genera (e.g., OrchestIn Tethorchestia, benthicsuperfamilies(e,g.,Ljeucothoidea),pairedischial
^
Piatorchestia, and a few primitive terrestrial genera lobesare present in the pow-erfully subchelate gnath-
(e,g., Cerrorchesria spp., Orchesiieila neambukws) opods & 2 of both sexes within family Pteustidae
I
(see Lindeman 1991; Friend 1987), They arc weakly (e.g., Pleusies fuberculalus, Thorlataoniusbofeaii:^)
developed or lackijig in sandhopper genera (e.g., [see Bousfield & Hendrycks 19941, family Amph-
Americorchesiia, Megalorchestia, Sinorchestia^ (see ilochidae (e,g., Apolochits lilomlis, Hemrstonius vU-
BousHeld 1982, 1992;Merino 1972). Hydrodynaniic ordes), and in males within superfamily Stenothoidea
lobesareweaklydevelopedonthebasisand ischiumof (e.g., Stenoihoe marifta, Metopeiln cingusta)r The
males withinsubfamilyChiltoniinae(Hyalellidae),but anteriorbasal lobesofgnadiopcxl2withintheCyamida
apparently not developed (secondarily lost?) in other (e.g., Cyamm^ Scidocyamus) may be considered hy-
families and subfamilies ofTaJitroidea. drodynamic lobes, even though the animal itself re-
Hydrodynamiclobesofgnathopodsareknownelse- mains stationary (Mareoiis et al 2000). The lobes
m
wherewithingammarideanarnphipods,but eshaus- presumably facilitate smooth lannnar flow' of strong
tfve review oftheiroccurrence is beyond thescope of watercurrentsresultingfrom rapidforwardswimming
thisstudy. Afewsamples may11lustrate thephenom- of the host cetacean, currents that might otherwise
enon. Thus,withintheadvanced tube-buildingsuper- dislodge theamphipodform itsflattenedectoparasidc
family Corophioidea, well developed lobesofsimilar positionon the whale's skin
type have been illustrated in the powerfullysubchelate By contrast, basal and ischial lobes are apparently
gnathoped 2 of males of family Ampithoidae (e.g.^ lithe develo|}ed within themainly marinesuperfamily
Ampithoe mlida. Peramphithoeplea)Jjim\\y Ischyro- Hadzioidea,orin the mainly freshwatersuperfamilies
ceridae(Ischyrocerusoahu,Parajassaangufarls),and GammaroideaandCrangonyctoidea,eveninfree-swim-
in some Isaeidae(e.g,, Pholtskapapa},and in gnathO' mingspeciesthatpossess powerfullysubchelatemale
AMPHIPAORCA VOL. 3 NO,3 Nov. 15. 2002. 25
BASISAND Plesiomorphic intermediate ApomOrphic
ISCHIUM Lobes large Lobes medium Lobes small
or lacking
GNATHOPOO
1
A. Male
B. Female y
R (Proiohyaie) Laptohya}e Parhyaie
GNATHOPOO2
C. Male
Parhys^
R (PTotohyaie) PUIohyale
D. Female
P.(Protohyaie) L&ptohyate Ptiiohyate
&
Fig. 4 Hydnxlynamic lobes ofbasal and ischial segments ofgnathpods 1 2 (lateral view)
in mature male and female hyalid amphipods: character states.
gnathopods. often ofpreamplexingfunction, Hydro- all fourcoxal plates of species ofadvanced saltatory
dynamiclobesarealsonotwell developedwithin most genera (e.g., Apokyaie, Fiilohyaie) within family
superfamtlicsof the "Natantia " taxonomiccategory^ HyaJidaeand most speciesoffamiIyTaliiridac(except
exceptinafew instances wheregnathopodsarepower- some sandhoppers). The cusps are limited to fewer
fully developed and shott-wristed (e g., Eusiroide^i coxae,ornone,inmainlyaquatichyaltdsandareabsent
diplonyx Barnard 970). from otherfamilies within theTalitroidea.
1
The balance of morphological evidence, mainly The function ofthe cusp has not been determined
withinsupertamilyTalitroidea.indicatesthatbasaland precisely. Itspresencemainlyin saltatory speciessug-
ischiallobesarebestdevelopedinpowerfullysubchelate gests that, during ajumping or springing action, the
gnathopods whichfold tightly intoa streamlined (hy- cusp prevents hyperspreading of the plates beyond
drodynamic) swimming position, presumably during mechanically safelimitsandthusensuresthatadjacent
preamplexing "carrying''ofthefemale. Exceptions to plates return to their properly overlapped deflexed
such generaJi^edobseiwations.especiallyamong non- positions ontermination ofsaltation.
talitroidean amphipods, suggest that full solution to Jn someprimitive saltatory groups{e.g„ Parhyak)^
theirfunctionality may require rigorousobservations adistinct cuspmaybelackingbutapostero-distalshelf
and high-speed photographyofswimmingamphipods isusually present. Theshelfmay besharply rounded
undercontrolled laboratory conditions. orshallow and nearly straightor imperceptible,espe-
ciallyon coxa I (e.g., in Hyakspp., Fig.46). In Par-
2.The posterior marginal cuspofcoxae 1-4 hyak,shortbluntcuspsareusuallypresentonthebroad
The posteriormarginofcoxal plates 1^frequently posteriorshelfofcoxae2&.3.butcoxa Ibearsa narrow
bearsamedian shortshaiplyroundedthumb-likeproc- shelf only. Also in Parhyale^ and some species of
essoracclivity (Barnard 1979), here termed the post- Protohyate, the proximal posterior margin typically
eriormarginal cusp (figs. 1E,2F). Thecuspoccurson bears abroadly obtuse cuspaboutmid point,
AMPHIPAORCA VOL 3 NO,3 Nov. 15, 20fl2. 26
Fig. 5. Final 6 stages (Nos. 8-13) of development ofgnathopod 2 in the male of
Frowhyale (F.) media (Dana) (medial view) (modified from Leite & Wakabara 1989).
11
.
Fig, 6. Final 6 stages (nos. S-I3) ofdevelopment of gnathopod 2 in the female of
Protohyale (P.) media (Dana) (medial view) (modified from Leite & Wakabara I9S9).